The invention relates to a paper feeder for use in a copying machine or facsimile system, and more particularly to such a paper feeder having a sheet separator which separates and feeds sheets one by one from a stack disposed on a paper tray.
A variety of sheet separating members or apparatus are known for feeding the uppermost sheet from a sheet stack on a paper tray by means of a feed roller. By way of example, a corner separator may be disposed at each corner of the leading end of the tray. Alternatively, an apparatus may be used which is adapted to feed the sheets one by one through a clearance having a gap length corresponding to the thickness of a single sheet. As a further alternative, a pair of oppositely rotating rollers may be disposed in mating relationship so that when a plurality of sheets are simultaneously fed from the paper tray, the uppermost sheet is fed in a given direction by one of the rollers, while the forward movement of the remaining sheet or sheets is blocked by the other roller.
However, these known sheet separators operate alone. In other words, the conventional paper feeder is only provided with a single separator, so that no remedy can be applied whenever the one separator fails to provide its intended separating operation, resulting in the inconveniences that two or more sheets may be fed into a sheet processing apparatus such as a copying machine of facsimile transceiver or a jamming of sheets may occur on a sheet passage which connects the paper feeder with the sheet processing apparatus. Such failure of sheet separation can be usually avoided where sheets of a kind which are compatible with a particular sheet separator are normally used. However, a variety of sheets are used in copying machines or facsimile systems, and hence a perfect sheet separating action cannot be expected from a single sheet separator for all kinds of sheets. In particular, in the facsimile transceiver, various kinds of sheets are used as an original for transmission. When they are disposed in a stack on the paper tray in order to be separated sheet by sheet, it is hardly possible to assure against the failure of sheet separation.